Hydrocarbon trap and method for manufacture

ABSTRACT

A hydrocarbon (HC) trap positioned in an intake conduit of an engine is provided. The HC trap includes a stack of consecutively layered polymeric sheets with at least a portion of the sheets impregnated with a HC vapor adsorption/desorption material, the stack of sheets extending from a first exterior surface to a second exterior surface.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/657,544, entitled “HYDROCARBON TRAP AND METHOD FORMANUFACTURE,” filed on Oct. 22, 2012, the entire contents of which arehereby incorporated by reference for all purposes.

FIELD

The present disclosure relates to a hydrocarbon trap in an intake systemof an engine.

BACKGROUND AND SUMMARY

Hydrocarbon (HC) vapors may emanate from the interior of an engine andescape through the engine's intake system. Therefore, HC traps are usedin internal combustion engines to capture hydrocarbon vapors which maybe otherwise leaked into the environment surrounding the engine. HCtraps therefore reduce emissions (e.g., evaporative emission) from theengine.

US 2005/0145224 discloses an evaporative emission storage device havingHC adsorption/desorption material positioned between porous polymericlayers. Hydrocarbon vapors may flow through the porous polymeric layersand into the HC adsorption/desorption material where the vapor isstored. The Inventors have recognized several drawbacks with theevaporative emission storage device disclosed in US 2005/0145224.Firstly, filling the area between the porous polymeric layers withadsorption material may involve a complicated and costly manufacturingprocess, increasing the cost of the vehicle. Additionally, the polymericlayers surrounding the adsorption material may limit the flow rate ofthe HC vapor into and/or out of the adsorption material. As a result,the amount of HC vapors captured by the storage device may be reduced,which may increase emissions (e.g., evaporative emissions). Furthermore,the profile of the HC trap may be increased when the polymeric materialis used to enclose adsorption material. Still further, it may bedifficult to provide a desired amount of rigidity to the storage devicevia the porous polymeric layers while at the same time providing thedesired adsorption and/or desorption rate of the HC vapor in the storagedevice. Therefore, tradeoffs between desired characteristic in thestorage device disclosed in US 2005/0145224 may be necessitated.

The Inventors herein have recognized the above issues and developed ahydrocarbon (HC) trap for an intake system of an engine. The HC trapincludes a stack of consecutively layered polymeric sheets at least aportion of the sheets impregnated with a HC vapor adsorption/desorptionmaterial, the stack of sheets extending from a first exterior surface toa second exterior surface.

The polymeric sheets serve multiple uses, providing structural integrityto the HC trap and providing HC adsorption via the adsorption/desorptionmaterial embedded within the sheets. Consequently, the adsorption and/ordesorption rate of HC vapors in the HC trap may be increased when HCadsorption material is integrated into the polymeric sheets. Moreover,the profile of the HC trap may be reduced, if desired, when the sheetsprovide both structural integrity as well as adsorption/desorptionfunctionality. Furthermore, the cost of the HC trap may be reduced whenthe polymeric sheets serve multiple purposes.

In one example, there may be no intervening adsorption/desorptionmaterial positioned between the sheets, such as carbon pellets. In thisway, the cost of the HC trap may be reduced via a reduction in materialsin the trap. It will be appreciated that the manufacturing cost of theHC trap may be reduced when the sheets are impregnated with HC vaporadsorption/desorption material and there is no adsorption/desorptionmaterial positioned between the sheets, due to the elimination of a stepof filling the area between the sheets with loose adsorption/desorptionmaterial.

The above advantages and other advantages, and features of the presentdescription will be readily apparent from the following DetailedDescription when taken alone or in connection with the accompanyingdrawings.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure. Additionally, the above issues have been recognizedby the inventors herein, and are not admitted to be known.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic depiction of an engine including a vapor purgesystem;

FIG. 2 shows an illustration of a HC trap in an intake conduit;

FIG. 3 shows an illustration of the HC trap shown in FIG. 2;

FIG. 4 shows a cross-sectional view of a portion of the HC trap shown inFIG. 3;

FIG. 5 shows a method for manufacturing a HC trap; and

FIG. 6 shows the intake gas-flow pattern in the engine shown in FIG. 1during engine shut-down.

FIGS. 2-3 are drawn approximately to scale, however other relativedimensions may be used if desired.

DETAILED DESCRIPTION

The following description relates to a hydrocarbon (HC) trap and methodfor manufacture of a HC trap. The HC trap may include a stack ofconsecutively layered polymeric sheets impregnated with HC vaporadsorption/desorption material. In this way, a single medium (i.e., thestack of sheets) may provide both adsorption functionality as well asstructural integrity to the HC trap. Specifically in some examples, nointervening adsorption/desorption material is positioned betweenadjacent polymeric sheets in the stack of sheets. In this way, thecomplexity of the HC trap may be reduced when compared to traps withadsorption/desorption material positioned within the trap. As a result,the manufacturing cost of the HC trap is reduced. Moreover, the profileof the HC trap may be reduced, if desired, when the stack of sheetsserves multiple uses.

FIG. 1 is a schematic diagram showing one cylinder of multi-cylinderengine 10, which may be included in a propulsion system of a vehicle 100in which an exhaust gas sensor 126 (e.g., air-fuel sensor) may beutilized to determine an air fuel ratio of exhaust gas produce by engine10. The air fuel ratio (along with other operating parameters) may beused for feedback control of engine 10 in various modes of operation.Engine 10 may be controlled at least partially by a control systemincluding controller 12 and by input from a vehicle operator 132 via aninput device 130. In this example, input device 130 includes anaccelerator pedal and a pedal position sensor 134 for generating aproportional pedal position signal PP. Cylinder (i.e., combustionchamber) 30 of engine 10 may include combustion chamber walls 32 withpiston 36 positioned therein. A cylinder head 80 is coupled to acylinder block 82 to form the cylinder 30.

Piston 36 may be coupled to crankshaft 40 so that reciprocating motionof the piston is translated into rotational motion of the crankshaft.Crankshaft 40 may be coupled to at least one drive wheel of a vehiclevia an intermediate transmission system. Further, a starter motor may becoupled to crankshaft 40 via a flywheel to enable a starting operationof engine 10.

Cylinder 30 may receive intake air from intake manifold 44 via intakeconduit 42 and may exhaust combustion gases via exhaust passage 48. Theintake manifold 44 may include an intake manifold, in some examples.Intake manifold 44 and exhaust passage 48 can selectively communicatewith cylinder 30 via respective intake valve 52 and exhaust valve 54. Insome embodiments, cylinder 30 may include two or more intake valvesand/or two or more exhaust valves. A throttle 62 including a throttleplate 64 is positioned in the intake conduit 42. The throttle isconfigured to adjust the amount of airflow flowing to the cylinder 30.

In this example, intake valve 52 and exhaust valves 54 may be actuatedvia an intake cam 51 and an exhaust cam 53. In some examples, the engine10 may include a variable cam timing system configured to adjust(advance or retard) cam timing. The position of intake valve 52 andexhaust valve 54 may be determined by position sensors 55 and 57,respectively.

Fuel injector 66 is shown arranged in intake manifold 44 in aconfiguration that provides what is known as port injection of fuel intothe intake port upstream of cylinder 30. Fuel injector 66 may injectfuel in proportion to the pulse width of signal FPW received fromcontroller 12 via electronic driver 68. In some examples, cylinder 30may alternatively or additionally include a fuel injector coupleddirectly to cylinder 30 for injecting fuel directly therein, in a mannerknown as direct injection.

Ignition system 88 can provide an ignition spark to cylinder 30 viaspark plug 92 in response to spark advance signal SA from controller 12,under select operating modes. Though spark ignition components areshown, in some embodiments, cylinder 30 or one or more other combustionchambers of engine 10 may be operated in a compression ignition mode,with or without an ignition spark.

Exhaust gas sensor 126 is shown coupled to exhaust passage 48 of exhaustsystem 50 upstream of emission control device 70. Sensor 126 may be anysuitable sensor for providing an indication of exhaust gas air/fuelratio such as a linear oxygen sensor or UEGO (universal or wide-rangeexhaust gas oxygen), a two-state oxygen sensor or EGO, a HEGO (heatedEGO), a NOx, HC, or CO sensor. In some examples, exhaust gas sensor 126may be a first one of a plurality of exhaust gas sensors positioned inthe exhaust system. For example, additional exhaust gas sensors may bepositioned downstream of emission control device 70.

Emission control device 70 is shown arranged along exhaust passage 48downstream of exhaust gas sensor 126. Emission control device 70 may bea three way catalyst (TWC), NOx trap, various other emission controldevices, or combinations thereof. In some examples, emission controldevice 70 may be a first one of a plurality of emission control devicespositioned in the exhaust system. In some examples, during operation ofengine 10, emission control device 70 may be periodically reset byoperating at least one cylinder of the engine within a particularair/fuel ratio.

Controller 12 is shown in FIG. 1 as a microcomputer, includingmicroprocessor unit 102, input/output ports 104, an electronic storagemedium for executable programs and calibration values shown as read onlymemory 106 (e.g., memory chip) in this particular example, random accessmemory 108, keep alive memory 110, and a data bus. Controller 12 mayreceive various signals from sensors coupled to engine 10, in additionto those signals previously discussed, including measurement of inductedmass air flow (MAF) from mass air flow sensor 120; engine coolanttemperature (ECT) from temperature sensor 112 coupled to cooling sleeve114; a profile ignition pickup signal (PIP) from Hall effect sensor 118(or other type) coupled to crankshaft 40; throttle position (TP) from athrottle position sensor; and absolute manifold pressure signal, MAP,from sensor 122. Engine speed signal, RPM, may be generated bycontroller 12 from signal PIP. Manifold pressure signal MAP from amanifold pressure sensor may be used to provide an indication of vacuum,or pressure, in the intake manifold. Note that various combinations ofthe above sensors may be used, such as a MAF sensor without a MAPsensor, or vice versa. During stoichiometric operation, the MAP sensorcan give an indication of engine torque. Further, this sensor, alongwith the detected engine speed, can provide an estimate of charge(including air) inducted into the cylinder. In one example, sensor 118,which is also used as an engine speed sensor, may produce apredetermined number of equally spaced pulses every revolution of thecrankshaft.

During operation, the cylinder 30 in the engine 10 typically undergoes afour stroke cycle: the cycle includes the intake stroke, compressionstroke, expansion stroke, and exhaust stroke. In a multi-cylinder enginethe four stroke cycle may be carried out in additional combustionchambers. During the intake stroke, generally, exhaust valve 54 closesand intake valve 52 opens. Air is introduced into cylinder 30 via anintake manifold, for example, and piston 36 moves to the bottom of thecombustion chamber so as to increase the volume within cylinder 30. Theposition at which piston 36 is near the bottom of the combustion chamberand at the end of its stroke (e.g. when cylinder 30 is at its largestvolume) is typically referred to by those of skill in the art as bottomdead center (BDC). During the compression stroke, intake valve 52 andexhaust valve 54 are closed. Piston 36 moves toward the cylinder head soas to compress the air within cylinder 30. The point at which piston 36is at the end of its stroke and closest to the cylinder head (e.g. whencylinder 30 is at its smallest volume) is typically referred to by thoseof skill in the art as top dead center (TDC). In a process hereinafterreferred to as injection, fuel is introduced into the combustionchamber. In a process hereinafter referred to as ignition, the injectedfuel is ignited by known ignition devices such as a spark plug 92,resulting in combustion. Additionally or alternatively compression maybe used to ignite the air/fuel mixture. During the expansion stroke, theexpanding gases push piston 36 back to BDC. A crankshaft may convertpiston movement into a rotational torque of the rotary shaft. Finally,during the exhaust stroke, exhaust valve 54 opens to release thecombusted air-fuel mixture to an exhaust manifold and the piston returnsto TDC. Note that the above is described merely as an example, and thatintake and exhaust valve opening and/or closing timings may vary, suchas to provide positive or negative valve overlap, late intake valveclosing, or various other examples. Additionally or alternativelycompression ignition may be implemented in the cylinder 30.

FIG. 1 also shows a HC trap 150 positioned in the intake conduit 42.Thus, the HC trap 150 is positioned upstream of the throttle 62.However, other suitable HC trap positions have been contemplated. The HCtrap 150 may be configured to adsorb HC vapors. The HC trap 150 isconfigured to adsorb and desorb HC vapors in the intake manifold 44. Itwill be appreciated that the HC trap 150 reduces emissions (e.g.,evaporative emissions) in the vehicle and captures HC vapors that mayotherwise flow into the surrounding environment, during for exampleengine shut-down. The HC trap 150 is depicted as a box in FIG. 1.However, detailed characteristics of the HC traps are discussed ingreater detail herein with regard to FIGS. 2-4.

An air filter 170 may also be positioned in the intake conduit 42. Theair filter 170 is configured to remove particulates from air flowingthrough the intake conduit 42. The air filter 170 spans the intakeconduit in the depicted example. However, other air filterconfigurations have been contemplated.

A drain 172 opening into the intake conduit 42 may also be included inthe engine 10. The drain 172 is configured to drain condensation fromthe intake conduit 42. The outlet of the drain may be positionedexternal to the engine 10, in some examples. As shown, the drain 172 ispositioned below the HC trap 150. However, other drain positions havebeen contemplated.

A second HC trap 174 may also be positioned in the intake conduit 42downstream of the HC trap 150. The second HC trap 174 spans the intakeconduit 42 in the depicted example and therefore may be referred to as aflow-through HC trap. However, other configurations of the second HCtrap have been contemplated. Further in some examples, the second HCtrap 174 may be omitted from the engine 10. A positive crankcaseventilation (PCV) port 176 opening into the intake conduit 42 may alsobe included in the engine 10. The PCV port 176 may be in fluidiccommunication with a crankcase in the engine 10. A cooler 178 may alsobe positioned in the intake conduit 42. The cooler 178 may be includedin the engine 10 when the engine is boosted via a compressor. It will beappreciated that in other examples the engine 10 may not include thecooler 178.

Arrows 180 depict the general flow of intake air through the engine'sintake system during engine operation when the engine is performingcombustion. FIG. 1 shows the engine during purging of the HC trap 150and the second HC trap 174 when HC vapors desorb from the HC traps. Asshown, intake air travels through the air filter 170. Air also entersthe intake conduit 42 from the drain 172. Arrows 182 denote the generalflow of HC vapors. As shown, HC vapors may flow from the HC trap 150 andthe second HC trap 174 in a downstream direction toward the throttle 62during engine operation. Arrows 184 denote the general flow of HC vaporsand intake air downstream of the second HC trap 174. As shown, intakeair and HC vapors flow into the PCV port 176 and downstream toward thethrottle 62. It will be appreciated that arrows 180, 182, and 184generally depict the direction of gas flow. However, the pattern ofintake air-flow and HC vapor-flow during engine operation may haveadditional complexity that is not depicted.

FIG. 6 shows the engine 10 and vehicle shown in FIG. 1 during engineshut-down when the engine is not performing combustion. Therefore,similar parts are labeled accordingly. Thus, FIG. 6 shows the engine 10during loading of the HC trap 150 and the second HC trap 174 when HCvapors adsorb into the HC traps. Arrows 600 depict the general flow ofHC vapors in the intake system during engine shut-down when the engineis not performing combustion.

It will be appreciated that HC vapors may flow from the combustionchamber 30 to the intake manifold 44 from the intake manifold 44 to theintake conduit 42. As shown, HC vapors also flow from the PCV port 176into the intake conduit 42. The HC vapors may flow through the second HCtrap 174 where a portion of the HC vapors may adsorb into the trap.Additionally, HC vapors may flow past the HC trap 150 which may alsoadsorb a portion of the HC vapors. Some HC vapors may also flow out ofthe drain 172 and the intake conduit 42 into the surroundingenvironment. However, it will be appreciated that the HC trap 150 andthe second HC trap 174 may adsorb a large portion of the HC vapors,thereby reducing evaporative emissions.

FIG. 2 shows an illustration of an example HC trap 150 in an upper halfof an air box which may be part of the intake conduit 42, shown inFIG. 1. The air box cover 250 is positioned upstream of the throttle 62,shown in FIG. 1, in the depicted example. However, in other examples theHC trap 150 and/or the second HC trap 174 shown in FIG. 1, may bepositioned downstream of the throttle.

The air box cover 250 includes structural reinforcing webbing 202. Thestructural reinforcing webbing 202 may increase the structural integrityof air box cover 250. The air box cover 250 further includes a flange204 which may be mated to the air filter located between the upper andlower halfs of the air box. The air box cover 250 further includes aninlet 208 and an outlet 206. Arrow 209 denotes the flow of intake airinto the air box cover 250 during engine operation when the engine isperforming combustion. However, it will be appreciated that duringengine shut-down air may flow in the opposing direction. The outlet 206may have a smaller cross-sectional area than the inlet 208. However,other geometries and sizes of the air box cover have been contemplated.It will be appreciated that the air box cover 250 is positioned upstreamof the throttle 62, shown in FIG. 1.

The HC trap 150 is coupled to the air box cover 250 via fasteners 200.Heat stakes are shown coupling the HC trap to the intake conduit in thedepicted example. Specifically, the heat stakes extend through openingsin the HC trap 150. Additionally or alternatively, sonic welds may alsobe used to couple the HC trap to the air box cover. However, othersuitable fasteners or attachment apparatuses may be used such as screws,bolts, adhesive, etc.

The HC trap 150 in FIG. 1 has a structure 210 as depicted in FIGS. 2 &3. The HC trap structure 210 may be configured to adsorb and desorb HCvapors in the air box cover 250. Continuing with FIG. 2, the HC trap 150includes flanges 212. One of the flanges 212 includes a reinforcing rib214.

The HC trap further includes raised sections 216, 217, 218, and 219. Thesize and geometry of the raised sections (216, 217, 218, and 219)varies. It will be appreciated that the variation in size and/orgeometry of the raised sections may be selected based on air-flowpatterns in the air box cover 250. This may enable the HCadsorption/desorption rate of the HC trap to be varied and allowimprovements to reduce air flow turbulence.

FIG. 3 shows a detailed illustration of the HC trap 150 shown in FIG. 2.As discussed above with regard to FIG. 2, FIG. 3 depicts the HC trapstructure 210. The HC trap structure 210 includes a first exteriorsurface 300 and a second exterior surface 302. The second exteriorsurface is positioned underneath the first exterior surface in thedepicted example. However, other relative positions have beencontemplated. It will be appreciated that intake air and HC vapors mayflow across the first exterior surface 300 and the second exteriorsurface 302 in the air box cover 250, shown in FIG. 2, during someengine operating conditions, such as during engine shut-down. A stack ofconsecutively arranged polymeric sheets may be positioned between thefirst exterior surface 300 and the second exterior surface 302. Theintermediate polymeric sheets are discussed in greater detail herein.Continuing with FIG. 3, portions of the raised sections (216, 217, 218,and 219) are included in the first exterior surface 300.

The first exterior surface 300 and the second exterior surface 302 maydefine a boundary of the HC trap structure 210. Edges 304 of sheetspositioned between the first exterior surface 300 and the secondexterior surface form a peripheral boundary of the adsorption structure210. In some examples, each of the sheets included in the stack ofsheets extends to the edges 304 of the HC trap structure 210. However,other sheet configurations have been contemplated. Thus, the first andsecond exterior surfaces and edges of the stack of sheets form aboundary of the HC trap structure, in the depicted example.

The first exterior surface 300 and/or second exterior surface 302 mayinclude a base polymeric material impregnated with a HC vaporadsorption/desorption material. The use of multiple thermoformedpolymeric material sheets provides structural integrity to the HC trapwhile retaining the adsorption/desorption functionality via theimpregnated HC vapor adsorption/desorption material. In this way, thebase polymeric material provides multiple functions. As a result, thecost and/or profile of the HC trap may be reduced, if desired.

The polymeric material may be non-woven polyester and the HC vaporadsorption/desorption material may be activated carbon, in someexamples. Additionally or alternatively, the HC vaporadsorption/desorption material may include carbon, activated carbon,zeolites, hydrophobic cellulose, silicon oils, cyclodextrins, and/or anyother suitable adsorption/desorption material. Specifically, in someexamples the first exterior surface 300 may include substantiallyidentical materials to the second exterior surface 302. However, inother examples, the first exterior surface and the second exteriorsurface may comprise different materials. Cutting plane 310 defines thecross-section shown in FIG. 4.

The first exterior surface 300 may be the surface of a first sheet(e.g., first polymeric sheet) and the second exterior surface may be thesurface of a second sheet (e.g., second polymeric sheet). The HC trapstructure 210 may also include a plurality of sheets positioned betweenthe first exterior surface 300 and the second exterior surface 302, aspreviously discussed. The sheets positioned between the first and secondexterior surfaces may include similar materials such as a polymericmaterial impregnated with HC vapor adsorption/desorption material. Theintermediary sheets are discussed in greater detail herein with regardto FIG. 4.

The HC trap structure 210 includes depressed sections 306. One or moreof the polymeric sheets in the depressed sections may be in face sharingcontact with adjacent sheets in the depressed sections 306.Specifically, in the depicted example all of the polymeric sheets are inface sharing contact with adjacent polymeric sheets in the depressedsections. In other words, each sheet in the stack of sheets may be inface sharing contact with an adjacent sheet. Thus, the depressedsections may extend through the entire stack of sheets. The sheets inthe depressed sections 306 may be thermally coupled. Therefore, in suchan example the depressed sections may be referred to as thermallycoupled sections. Specifically, in the thermally coupled sections two ormore sheets may be thermally bonded. In other examples, one or more ofthe sheets in the depressed sections may be spaced away from adjacentsheets. Further in some examples, the thermally coupled sections mayretain the individual layers. It will be appreciated that the depressedsections may be thermoformed. That is to say that heat and/or pressuremay be used to construct the depressed sections. Specifically in someexamples, the whole HC trap 150 may be thermoformed. However, other HCtrap construction techniques have been contemplated. Additionally, thedepressed sections 306 traverse the HC trap 150. Furthermore, thethickness of the depressed sections 306 is less than the thickness ofthe raised sections (216, 217, 218, and 219). In some examples, thethermally coupled sections may retain individual layers. However, inother examples, the thermally coupled layers may be thermally coupled toform a continuous layer. Additionally, the thermally coupled section mayprovide enough rigidity such that additional supporting structures arenot included in the HC trap, if desired. Furthermore, the thermallycoupled sections may include attachment features for mounting andretention of the HC trap, such as the attachment features 330. In thedepicted example, the attachment features are openings. However, otherattachment features have been contemplated. Additionally, the thermallycoupled sections may also provide alignment features and may provide fitto a three dimensional contoured surface, as shown in FIG. 2. Thethermally coupled sections may also provide a desired amount of rigidityto reduce flutter of the adsorption material.

Continuing with FIG. 3, an angular separation 320 between a firstportion 322 of the first exterior surface 300 and a second portion 324of the first exterior surface is approximately 90°. However, other HCtrap geometries have been contemplated. The HC trap 150 also includesopenings 330 configured to receive coupling apparatuses, such as boltsfor attaching the HC trap 150 to the air box cover 250, shown in FIG. 2.

Further in some examples, the thermoformed HC trap structure 210provides enough rigidity such that additional supporting structures(e.g. cage) may not be used, if desired. In this way, the HC trap mayhave a desired amount of structural integrity simplifying theinstallation and/or replacement process. The HC trap 150 shown in FIG. 3does not include any additional components, such as a frame.Consequently, the cost of the HC trap may be reduced. It will beappreciated that the HC trap structure 210 may provide a desired amountof structural integrity to the HC trap. Therefore, the HC trap may onlyinclude the HC trap structure 210, in some examples. However, additionalcomponents may be included in the HC trap in other examples, if desired.

FIG. 4 shows a cross-sectional view of the HC trap 150, shown in FIG. 3.As shown, a plurality of polymeric sheets 400 are positioned between thefirst exterior surface 300 and the second exterior surface 302. In thisway, a stack of polymeric sheets extends from the first exterior surface300 to the second exterior surface 302. As illustrated, the firstexterior surface is included in a first exterior polymeric sheet 410 andthe second exterior surface is included in a second exterior polymericsheet 412. In this way a first polymeric sheet, included in theplurality of sheets 400, forms the first exterior surface 300 and asecond polymeric sheet, included in the plurality of sheets, forms thesecond exterior surface 302.

Each of the polymeric sheets may comprise similar materials. Forexample, each of the polymeric sheets may be a non-woven polyester sheetimpregnated with a HC vapor adsorption/desorption material such asactivated carbon. However, in other examples, not all sheets in thestack may be impregnated and by this manner the thickness may becontrolled without varying the adsorption/desorption characteristics.Therefore, only a portion of the sheets may be impregnated with HC vaporadsorption/desorption material, in some examples. As shown, each of theintermediary polymeric sheets 400 is spaced away from one another.However, in other examples two or more of the intermediary polymericsheets may be in face sharing contact. Each of the polymeric sheets 400has an equivalent thickness in the depicted example. However, in otherexamples, the thicknesses of the polymeric sheets may vary from sheet tosheet or vary along the length and/or width of each sheet.

The plurality of sheets 400 may be referred to as a stack of sheets. Theplurality of sheets is consecutively layered and there may be noadsorption material positioned between the sheets. The stack of sheets400 is formed into a single unitary rigid structure (i.e., the HC trapstructure 210 shown in FIG. 3), in the depicted example. However, inother examples the stack of sheets may form multiple structures and/orone or more of the structures may be flexible. However, rigidstructure(s) may be used in the HC trap to simplify installation and/orreplacement. The adsorption/desorption material impregnated into thepolymeric sheets may include carbon, activated carbon, zeolites,hydrophobic cellulose, silicon oils, and cyclodextrins. The spacesbetween sheets may not include loose adsorption particles such as carbonpellets, zeolites, hydrophobic cellulose, silicon oils, cyclodextrins,or other adsorption material. However, in other examples, looseadsorption/desorption material may be positioned between the sheets.Further in some examples the HC trap structure may not include adhesivebetween the sheets.

Specifically, in the depicted example, there is no intervening materialpositioned between the plurality of sheets included in the stack ofsheets 400. In this way, the complexity of the HC trap may be reducedwhen compared to traps with loose adsorption material positioned betweenlayers in the trap. As a result, the cost of the HC trap is reduced.Moreover, the profile of the HC trap may be reduced, if desired. Asshown, gaps 404 are positioned between adjacent sheets in the pluralityof sheets 400. The gaps may be filled with a gas such as air. In thisway, no intervening material may be positioned within the gaps 404. Itwill be appreciated that the cross-section shown in FIG. 4 is a crosssection of the raised section 219, shown in FIG. 3. Further it will beappreciated that the other raised sections may have a similarcross-section. Additionally, the depressed sections 306 shown in FIG. 3may have smaller gaps between the sheets or adjacent sheets in the stackof sheets may be in face sharing contact. Further it will be appreciatedthat each of the sheets 400 may extend to the edges 304, shown in FIG.3, in some examples. However in other examples, one or more of thesheets 400 may not extend to the edges 304, shown in FIG. 3.

FIG. 5 shows a method 500 for manufacturing a HC trap. The method 500may be used to construct the HC trap discussed above with regard toFIGS. 1-4 or may be used to construct another suitable HC trap.

At 502 the method includes impregnating a stack of polymeric sheets withthe HC vapor adsorption/desorption material. Next at 504 the methodincludes stacking consecutively layered polymeric sheets impregnatedwith the HC vapor adsorption/desorption material extending from a firstexterior surface to a second exterior surface, the stack ofconsecutively layered polymeric sheets having no adsorption materialpositioned between the sheets. At 505 the method includes thermoformingthe HC trap. The HC trap includes the stack of consecutively layeredpolymeric sheets. Thermoforming the HC trap may include press-formingthe stack of consecutively layered polymeric sheets to a desired3-dimensional shape via mating dies at 506. Thermoforming the HC trapmay also include at 508 fusing a plurality of polymeric sheets in thestack of consecutively layered polymeric sheets together in selectedareas through the introduction of heat to the mating dies. In this way,rigidity may be provided to the HC trap in selected areas as well asbonding (e.g., permanently bonding) the multiple layers together. At 510the method includes die cutting to package, size HC trap for adsorptivecapacity and provide attachment/alignment features. Die cutting the HCtrap may include die cutting the perimeter edges of the HC trap and/ordie cutting attachment features (e.g., attachment openings) to packageattach, size trap capacity, etc. Step 510 may be performed while the HCtrap is in a thermoforming machine. Thus, the die cut may be edge firedduring thermoforming to reduce edge fraying. Therefore, step 510 may beincluded in step 504, in some examples. As previously discussed, thesheets may be positioned adjacent to one another without any interveningmaterial and the polymeric sheets may be non-woven polyester and the HCvapor adsorption/desorption material may be activated carbon. In thisway, a simplified manufacturing process may be used to construct a HCtrap which does not involve filling areas in the trap with looseadsorption/desorption material.

Various steps, acts, operations, etc., illustrated may be performed inthe sequence illustrated, in parallel, or in some cases omitted.Likewise, the order of the steps is not necessarily required to achievethe features and advantages of the example embodiments described herein,but is provided for ease of illustration and description. One or more ofthe illustrated steps may be repeatedly performed depending on theparticular method being used.

It will be appreciated that the configurations and methods disclosedherein are exemplary in nature, and that these specific embodiments arenot to be considered in a limiting sense, because numerous variationsare possible. For example, the above technology can be applied to V-6,I-4, I-6, V-12, opposed 4, and other engine types. The subject matter ofthe present disclosure includes all novel and non-obvious combinationsand sub-combinations of the various systems and configurations, andother features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

The invention claimed is:
 1. A system, comprising: an engine having anair intake air conduit with an air box; and a hydrocarbon (HC) trappositioned inside the air box and contained within the air box, the HCtrap including a stack of consecutively layered polymeric sheets with atleast a portion of the sheets impregnated with a HC vaporadsorption/desorption material, the stack of sheets extending from afirst exterior surface to a second exterior surface, the stack of sheetsincluding a first raised section, the stack of sheets having oppositeends each having a bend, the HC trap coupled to the air box via heatstakes extending through openings in the HC trap.
 2. The system of claim1, further comprising a reinforcing rib extending along a flange of thestack, where the stack of sheets has no adsorption/desorption materialpositioned between the sheets, and wherein the sheets are formed into aunitary rigid structure, the flange coupled to the air box.
 3. Thesystem of claim 2, where the stack of sheets includes a second raisedsection having at least one of a different size and geometry than thefirst raised section, the bend positioned along a corner of an interiorof the air box.
 4. A hydrocarbon (HC) trap positioned in an intakeconduit of an engine comprising: a stack of consecutively layeredpolymeric sheets with at least a portion of the sheets impregnated witha HC vapor adsorption/desorption material, the stack of sheets extendingfrom a first exterior surface to a second exterior surface, the stack ofsheets including a first raised section, the stack of sheets havingopposite ends each having a bend.
 5. The HC trap of claim 4, furthercomprising a reinforcing rib extending along a flange of the stack,where the stack of sheets has no adsorption/desorption materialpositioned between the sheets, and wherein the sheets are formed into aunitary rigid structure.
 6. The HC trap of claim 5, where the HC vaporadsorption/desorption material includes one or more of carbon, activatedcarbon, zeolites, hydrophobic cellulose, silicon oils, cyclodextrins orany other HC adsorbing/desorbing materials.
 7. The HC trap of claim 5,where the HC vapor adsorption/desorption material includes looseadsorption particles.
 8. The HC trap of claim 4, further comprisingfasteners for coupling to an air box.
 9. The HC trap of claim 4, wherethe HC trap does not include adhesive between the sheets.
 10. The HCtrap of claim 4, where the sheets are non-woven polyester sheets and theHC vapor adsorption/desorption material is activated carbon.
 11. The HCtrap of claim 4, where a first polymeric sheet, included in the stack ofsheets, forms the first exterior surface and a second polymeric sheet,included in the stack of sheets, forms the second exterior surface. 12.The HC trap of claim 4, where each sheet in the stack of sheets is inface sharing contact with an adjacent sheet.
 13. The HC trap of claim 4,where the first and second exterior surfaces and edges of the stack ofsheets form a boundary of the HC trap structure.
 14. The HC trap ofclaim 4, where the stack of sheets includes a second raised sectionhaving at least one of a different size and geometry than the firstraised section.
 15. The HC trap of claim 14, where the thermally coupledsection retains the individual layers and provides enough rigidity suchthat additional supporting structures are not included in the HC trap.16. The HC trap of claim 14, where the thermally coupled sectionincludes attachment features for mounting and retention of the HC trapand where the thermally coupled section provides alignment features. 17.The HC trap of claim 14, where the thermally coupled section providesfit to a three dimensional contoured surface.
 18. The HC trap of claim4, where the stack of sheets includes a thermally coupled sectiontraversing the HC trap structure and includes two or more thermallybonded sheets where the thermally coupled section extends through thestack of sheets.
 19. A hydrocarbon (HC) trap in an intake conduit of anengine, comprising: a stack of consecutively layered non-woven polyestersheets impregnated with activated carbon extending from a first exteriorsurface to a second exterior surface, each of the sheets positionedadjacent to one another without any intervening adsorption/desorptionmaterial positioned between the sheets, the interveningadsorption/desorption material includes one or more of carbon, activatedcarbon, zeolites, hydrophobic cellulose, silicon oils, cyclodextrins,and any other HC adsorption/desorption material, the stack of sheetshaving opposite ends each having a bend.
 20. The HC trap of claim 19,where the stack includes a first raised section having a different sizeand/or geometry than a second raised section where the sheets in thefirst and second raised sections have gaps between the sheets with nointervening material position within the gaps.